Surgical sutures customarily are attached to a metallic surgical needle in order to facilitate use of the suture-needle combination during a surgical procedure. Pull out forces for permanent and removable needles are defined in the United States Pharmacopoeia XXII (1990), hereby incorporated by reference.
Sutures historically have been attached to needles by swaging or crimping the suture into the blunt end of the needle. In one known method, a channel is formed in the barrel end of the needle by splitting the barrel longitudinally. The suture tip is placed into the channel and the channel is crimped to grip and hold the suture tip to the needle. In another known attachment method, a cylindrical hole is drilled along the longitudinal axis of the needle and through the end face of the needle barrel section. The drilled hole generally is formed by mechanical or laser drilling. As shown in FIG. 1, in this attachment method a suture tip 1 is inserted into the drilled hole 2 and the barrel end of the needle is swaged or crimped in a region 3 which extends a distance from the end face 4 of the needle sufficient to securely hold the suture to the needle. This attachment method suffers from several drawbacks. One disadvantage is that crimping the needle barrel end out to the end face 4 brings the needle bore edge 5 in close contact with the suture, potentially creating a weakened suture portion immediately adjacent the needle suture attachment. More specifically, during suturing the needle may be angled relative to the suture, effectively causing the needle bore edge 5 to cut into and potentially weaken the suture tip 1. Furthermore, in order to obtain the desired attachment, the needle bore diameter, suture tip diameter and swaging or crimping force must be balanced to achieve the desired holding force. Because a wide variety of suture size and needle combinations are desired, the manufacturer must maintain a large inventory of various needle sizes and configurations having different bore hole diameters, and must standardize attachment dies, procedures and equipment to repeatedly provide consistent attachments. Of course, swaging equipment is subject to wear and variability during use, so careful attention must be paid to equipment maintenance if consistent swaging force and, hence, needle suture attachment is to be obtained. For example, if insufficient inward swaging force is applied by the die to the needle barrel, the compression gripping of the needle on the suture may be insufficient and the suture may pull out from the needle under too little force to meet specification. Conversely, where excessive inward swaging force is applied, the excessive compression gripping force exerted on the suture causes the suture tip to become crushed and weakened, thereby reducing the strength of attachment and the suture pull out force.
In view of these and other shortcomings of traditional needle suture attachment methods and apparatus, it would be desirable to provide a needle suture attachment which substantially eliminates the risk of a needle bore edge cutting into and weakening the suture. In addition, it would be desirable to provide a needle suture attachment method and apparatus which reduces the inventory of needles which must be maintained to facilitate attachment of multiple suture sizes to different needles, and provides consistent attachment with reduced maintenance and waste.
In addition, it would be desirable to provide a needle configuration which facilitates connection to a variety of suture sizes so as to reduce the inventory of needles which must be maintained. Further, it would be desirable to provide a needle construction which can be attached to a variety of suture sizes using substantially the same swaging force without the need to adjust swaging equipment or processes, thereby reducing needle attachment process and equipment maintenance. Finally, it would be desirable to provide a needle construction and attachment which have reduced sensitivity to variations in swaging force.